It is known to provide computed tomography (CT) scanning systems with a gantry formed as a centrally apertured disk or drum rotatable within a frame. However, these CT scanners use a two-dimensional fan beam tomography, which is a precursor of three-dimensional CBCT. Fan beam CT scanners are equipped with an array of multiple one-dimensional detector elements that detect a fan-shaped beam of X-rays from a gated radiation source. Three-dimensional image information is acquired by rotating the multi-detector array and X-ray source in a spiral or helical fashion to achieve lateral displacement of the subject and detector array. The need for helical displacement makes gantries for conventional fan beam tomography systems complex and cumbersome.
CBCT systems have numerous advantages over fan beam CT scanners due to their capacity to acquire three-dimensional image data with only a single revolution of the detector-radiation source arrangement. These advantages include reduced scan time, reduced radiation dose and improved image accuracy. State of the art CBCT systems typically employ a C-arm-mounted detector and cone beam X-ray source. The C-arm mount is commonly used in clinical dentistry, for example, to acquire volumetric image information of a patient's head while the patient stands or sits. In contrast to horizontally disposed cylindrical gantry systems, the C-mount does not allow volumetric, total-body scanning. As such, conventional CBCT systems cannot be cost-effectively applied as total body scanners.